NL1038101C2 - A method of collecting oil from a natural body of water. - Google Patents

Description

A method of collecting oil from a natural body of water

The present invention relates to a method of collecting oil from a natural body of water.

5 Oil spills such as the spill the result of the breaking of a pipeline - e.g. in a recent accident in the Gulf of Mexico (2010) -or the sinking of a crude carrier are quite detrimental to the environment. However, mopping up spilled hydrocarbons is quite a challenge. Various techniques have been proposed and even tried in prac-10 tice with varying degrees of success.

The object of the present invention is to provide a simple and environmentally acceptable method to collect at least part of the oil.

To this end, the invention according to the preamble is charac-15 terized in that the method involving the use of sphagnum fibers having a water content of less than 10% by weight of water, contacting the sphagnum fibers with water from which oil has to be collected so as to allow said sphagnum fibers to absorb hydrocarbons and separating the sphagnum fibers containing hydrocarbons from the water.

20 Thus the objective of the present invention is achieved. The water separated from the hydrocarbon-containing sphagnum fibers will be returned to the natural body of water. It is should be noted that the sphagnum fibers with the specified water content no longer absorb water in a reasonable length of time. Thus, the water content is that 25 of the sphagnum fibers, and any extraneous water in which they may be added to the oil-containing sand is not to be taken into account. By way of example, if sphagnum fibers are suspended in water, it is the water content before the sphagnum fibers are added to the water that counts .

30 According to a preferred embodiment, the method involves the steps of a) adding sphagnum fibers having a water content of less than 10% by weight of water to the surface of the natural body of water, so as to allow said sphagnum fibers to absorb hydrocarbons; and 35 b) collecting the sphagnum fibers containing hydrocarbons from the surface of the body of water.

While in the form of fibers, sphagnum fibers comprising oil hydrocarbons tend to form a cake that facilitates collecting thereof.

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Any sphagnum fibers not collected do not cause pollution of the body of water itself, the sphagnum fibers being an entirely natural and biodegradable product.

According to a preferred embodiment, the natural body of water 5 is a sea.

In the present application, the term sea includes ocean or other natural body of salt water. Collecting oil from the surface of a sea is in particular difficult due to the presence of waves, but feasible using the method according to the present invention. The 10 continuous motion of the waves helps to bring fibers into contact with the oil on the surface of the body of water.

According to a preferred embodiment, the sphagnum fibers added have a water-content of 4-8% by weight of water.

This allows for an optimum absorbance of the hydrocarbons by 15 the sphagnum fibers.

According to a preferred embodiment, an elongated floating barrier is used to define a closed area from which oil will be collected, where the surface area of the closed area provided with sphagnum fibers is reduced so as to facilitate collecting of the 20 sphagnum fibers containing hydrocarbons.

This method is similar to fishing, where a net may be cast wide and then drawn in, except that here the collecting is at the surface of the body of water.

According to a preferred embodiment, sphagnum fibers are added 25 along the circumference of the elongated floating barrier used to define a closed area.

This makes it possible to cover a very large surface area because it is not necessary to provide the full surface of the closed area with sphagnum fibers. When the surface area is reduced, the 30 sphagnum fibers will come into contact with oil not previously contacted with sphagnum fibers, allowing this oil to be absorbed as well.

According to a preferred embodiment, the sphagnum fibers are added to the surface of water while the elongated floating barrier is 35 provided on the surface of the natural body of water.

This makes the method according to the invention very efficient (less time consuming).

3

According to a preferred embodiment, oil-containing water is collected from the surface of the natural body of water, and passed over a bed comprising the sphagnum fibers.

Collecting oil-containing water from the surface of the natural 5 body of water may be done using arms extending from a ship, as is known in itself in the art.

According to a preferred embodiment, water from a first bed is passed over a further bed before being returned to the body of water, the further bed being used as a first bed once the oil content of the 10 sphagnum fibers starts to increase.

The beds are used in rotation. For example, there may be three beds. A first bed, a second bed and a third bed, two of which are used at any one time for absorbing hydrocarbons while one is prepared with fresh sphagnum fibers. Once the first bed starts to lose its ef-15 fectiveness in absorbing hydrocarbons, the second bed is used as the first bed and the third bed is used as the second bed. The bed material of the first bed is replaced with fresh sphagnum fibers to be ready once the former second bed (now the new first bed) starts to lose its effectiveness. The increase is, for example an increase to 20 more than 25% of the full hydrocarbon-absorbing capacity of the sphagnum fibers, such as an increase to more than 50%. Lower percentages translate into lower residual hydrocarbon residue in the water that will be discharged, but may make recuperation of absorbed hydrocarbons from the hydrocarbon-containing sphagnum fibers harder.

25 According to a preferred embodiment, sphagnum fibers containing hydrocarbons are subjected to a step of separating hydrocarbons from the sphagnum fibers containing hydrocarbons.

The hydrocarbons obtained can be put to good use, for example as a fuel or as a feedstock, making the method according to the in-30 vention more economically attractive. In general, it will be preferred if the cake of sphagnum fibers is strained first so as to remove any water that may adhere or present in pockets in the cake. The sphagnum fibers containing hydrocarbons are, for example, the sphagnum fibers containing hydrocarbons collected from the surface of the 35 natural body of water.

The present invention will now be illustrated with reference to the following example.

4

The method according to the present invention may be performed in various ways, for example using a ship provided with arms is used for collecting oil-contaminated water from the sea. Such a ship and this method of collecting oil-contaminated water is prior art.

5 In accordance with a first embodiment of the invention the oil- contaminated water is passed over two consecutive beds of sphagnum fibers (commercially available from various sources, such as Haro-Sorb, Haro Nederland B.V., Twisk, The Netherlands) having a water content of 7% by weight for absorbing oil present in the water. If 10 there is very much oil present in the water, it may be advantageous to use a pre-processing step, such as centrifugation, to eliminate part of the oil. This prevents the bed for getting saturated with oil quickly, and helps to eliminate oil from the water to a larger extent. The water passed over the bed is discharged back into the sea. 15 Once the upstream bed becomes saturated with oil, the down stream bed is used as the upstream bed, and another bed with fresh sphagnum fibers is used as the downstream bed.

The sphagnum fibers having a high content of hydrocarbons may be subjected to compaction to squeeze out at least part of the hydro- 20 carbons. The sphagnum fibers so obtained may be used again as bed ma terial for a limited number of times. Once they can no longer be used, they may be burned so as to use their caloric content.

The method according to the present invention can be varied in several ways within the scope of the appended claims. For example, 25 sphagnum fibers may be blown on the surface of the sea, using means known in the art for pneumatic transport such as a sidechannel pump or a claw pump, and subsequently collected from the surface of the natural body of water using a floating barrier. While may be advantageous to aim sphagnum fibers at a patch of oil, which gives the fi-30 bers more time to absorb, the fact that the floating barrier is reeled in like a net, the surface encompassed by the floating barrier is reduced and the sphagnum fibers will come into contact with the oil anyway.

1038101

Claims (10)

A method for collecting oil from a natural water body, characterized in that the method comprises the use of sphagnum fibers with a water content of less than 10% by weight of water, the sphagnum fibers having water from which oil must be are collected so that said sphagnum fibers can absorb hydrocarbons and hydrocarbon-containing sphagnum fibers are separated from the water. A method according to claim 1, wherein the method comprises the steps of a) applying 15 sphagnum fibers to the surface of the natural body of water with a water content of less than 10 weight percent water, so that said sphagnum fibers can absorb hydrocarbons; and b) collecting the hydrocarbon-containing sphagnum fibers from the surface of the body of water. 20 Method according to claim 1 or 2, wherein the natural body of water is a sea. 4. A method according to any one of the preceding claims, wherein the sphagnum fibers added have a water content of 4-8% by weight of water. 5. A method according to any one of the preceding claims, wherein an elongated floating barrier is used to define a closed area from which oil will be collected, wherein the area of the closed area provided with sphagnum fibers is reduced in order to collect the hydrocarbon. containing sphagnum fibers. The method of claim 5, wherein sphagnum fibers are added along the perimeter of the elongated floating barrier used to define a closed area. 1038101 The method of claim 5 or 6, wherein the sphagnum fibers are applied to the water surface while the elongated floating barrier is provided on the surface of the natural body of water. 5 A method according to any one of the preceding claims, wherein oil-containing water is collected from the surface of the natural body of water and guided over a bed comprising the sphagnum fibers. 10 9. Method as claimed in claim 8, wherein water from a first bed, before being returned to the body of water, is passed over a further bed, the further bed being used as a first bed as soon as the oil content of the sphagnum fibers starts to increase to take. 10. A method according to any one of the preceding claims, wherein the hydrocarbon fen-containing sphagnum fibers are subjected to a step of separating hydrocarbons from the hydrocarbon-containing sphagnum fibers. 1038101